Historically, the production of a colored image onto textile fabrics or cloth has been accomplished using screen printing techniques which require an image bearing screen for each color to be printed. Screen-printed images or patterns are transferred to the fabric by sequentially forcing ink of different colors through the screen to replicate the colors in the image. Such processes are expensive and time consuming even with mechanical assistance since separate artwork and printing steps are required for each color in the image to be printed.
Ink-jet printing, where minute droplets of ink are formed by various mechanisms and injected from nozzles onto a target surface, is capable of more rapidly generating multi-colored images and has recently begun to be used when printing on fabric. In order to produce an imaged pattern having desired sharpness, a combination of image resolution and color clarity, and permanence, ink-jet printing on fabric has generally been found to require special fabrics and pre-processing treatments. Moreover, since ink-jet printers are designed to print on paper, the fabric to be printed is typically backed with a special paper layer or else the cloth is pre-treated with organic materials intended to increase ink receptivity and reduce the amount of image spread, arising from bleeding of printed inks. An existing need within the industry is to provide ink-jet printed color images with the desired levels of sharpness and permanence without these special requirements.
Special inks for ink jet printing on fabric have also been developed to have durability in wearing and washing at the same time being printable onto fabric without undue bleeding of the image. These inks are made from a variety of dyes including disperse dyes, acid dyes, and reactive dyes, and may be used singly or in combination.
A specialty industry for screen printing, particularly onto cotton tee-shirts, has grown rapidly as a result of trends toward personality individualization. The creation of personalized, creative designs or images using a personal computer system loaded with graphic image applications has not eliminated the use of transfer sheets since ink jet printing machines are designed to operate with flat paper and these are not suited to handle cloth materials, especially fabrics which have uneven surfaces or seams between sections. In addition, the size of the image to be printed is limited to the size of paper normally feed through ink-jet printing machines and thus existing ink-jet printers are not well suited for volume production of large rolls of textile fabrics.
Examples of known art that has been developed to facilitate printing on textile fabrics with ink-jet techniques include U.S. Pat. No. 5,594,485 wherein ink jet printing is disclosed on a silk cloth composed mainly of fibers with special dernier and moisture characteristics, the suitability of silk being dependent from its fibrin sericin protein filament polymeric base formed through amino-acid condensation. To enhance image sharpness, the moisture percentage of the silk cloth is controlled by adding a metallic salt or a water-soluble high molecular weight polymer into the silk cloth.
U.S. Pat. No. 5,500,023 discloses an ink-jet printing process in which ink droplets of at least two inks of different colors are applied to a cloth to form a pattern, following which the cloth is subjected to a heat treatment to fix dyes contained in the cloth, and the, the cloth is washed to remove unfixed dyes from the cloth. In this process, the inks comprise water and an organic solvent and the individual reactive dyes have different reaction rates.
U.S. Pat. No. 5,403,358 discloses ink jet printing on cloth using a reactive dye that is enhanced by pre-treating the cloth with a color enhancing agent which comprises urea and a quaternary ammonium compound.
U.S. Pat No. 4,969,951 discloses an ink jet printing ink comprising a reactive disperse dye dispersed or dissolved in an aqueous liquid medium and then subjecting the cloth to dye fixing treatment. The reactive disperse dyes are slightly water-soluble azo or anthraquinone or other types of dyes having groups which can react with hydroxyl or amino groups of the fibers to form covalent bonds with the fibers.
U.S. Pat. No. 4,725,849 describes an ink-jet system for printing on pretreated cloth where the surface of cloth to be printed is previously provided with an ink-receiving hydrophilic resin solution.
U.S. Pat. No. 4,702,742 describes an ink jet printing process for textile printing which deposits an receptor material for ink onto the cloth to be printed, the receptor including natural and synthetic polymers, such as wheat flour rice powder and polyamides. To reinforce the adhesion of the ink acceptor to a substrate, a latex binder may be used.
U.S. Pat. No. 4,547,786 describes an ink jet printing system wherein a plurality of rigid panels are moved edgewise and rectilinearly in succession past an ink jet printing station by an endless carrier so that the ink jet printing head scans a line on each panel as it passes the printing station. Each ink jet printing head is moved in a direction perpendicular to the path of panel movement, in coordination with the panel movement to cause the head to scan a new line on the panel each time the panel passes the printing station.
U.S. Pat. No. 4,116,626 describes an textile carpet printing system in which a series of gun bars, each containing plural dye jets extending across the width of an endless conveyor, each gun bar having a plurality of individual jet orifices, each of the different gun bars containing a different color dye.
In view of the foregoing discussion, it is believed to be advantageous to provide a method for ink jet printing on fabric which does not require a special type of fabric or special pre-treating of the fabric, and which does not use backing or transfer papers to produce a printed image having a desired level of sharpness and permanence. Another shortcoming not addressed in the prior art is the ability to print patterns on fabrics having irregular surface features, such as seams or pockets, and on fabrics not having the thin, flat and uniform thickness properties of paper. A further shortcoming not addressed in the industry is the ability to continuously print patterns on large quantities of fabric using ink jet methods.